Fever can be concerning for parents, but it is a natural response to infection and an important part of the body’s immune defense. Understanding when to treat a fever, when to seek medical care, and how to keep your child comfortable can help ease anxiety and ensure proper care.
What Is a Fever?
A fever is a temporary increase in body temperature, often caused by infections like colds, flu, or other illnesses. While a normal body temperature varies, a fever is typically defined as 100.4°F (38°C) or higher.
Defining Fever in Children
- Pediatric temperature studies have used large population data to determine fever thresholds.
- 100.4°F (38°C) is the widely accepted threshold for fever in medical practice. This standard is based on both historical data and modern pediatric research.
- Pediatricians also focus on behavior and symptoms rather than just the number on the thermometer. For example, a child with a low-grade fever but dehydration or lethargy may need more attention than a child with a higher fever who is active and drinking fluids.
- Advancements in thermometry, including ear (tympanic), forehead (temporal), and digital oral thermometers, have improved fever detection. However, variations in readings across methods make it essential to interpret temperature alongside a child’s overall health and symptoms.
- The key takeaway: fever is a symptom, not an illness, and how a child looks and feels is just as important as the temperature reading itself.
Why Does My Child Have Chills with a Fever?
It’s common for children with a fever to experience chills or shivering. This happens because the body is raising its internal temperature to fight off infection. The brain signals the muscles to contract (shiver), generating heat to help reach the new set temperature.
If your child has chills, dress them in light layers and offer a warm blanket until the shivering stops. Avoid bundling them too much, as overheating can make them uncomfortable.
How to Keep Your Child Comfortable
If your child is generally acting well, a fever does not always need to be treated. The fever is working to get rid of an underlying infection, so let it do its job! The goal is to keep them comfortable rather than simply lowering the temperature.
Here are some tips for home management:
- Encourage fluids: Fever can lead to dehydration, so offer water, breast milk, formula, broth or electrolyte solutions.
- Dress lightly: Overdressing can trap heat. Use light clothing and a breathable blanket if needed. (Note: if your child feels cold, add layers for comfort - see the section on chills above.)
- Adjust room temperature: Keep the room at a comfortable temperature — not too hot nor too cold.
- Use fever reducers if needed: If your child is uncomfortable, acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) can help. Follow dosing instructions carefully based on age and weight. (Acetaminophen should not be given under 2 months and Ibuprofen should not be given until 6 months of age.) See our Medication Dosing Page for dosing information.
- Avoid cold baths or rubbing alcohol: These methods can cause chills and make your child feel worse.
Fever Facts
There are many misconceptions about fever. Here are some facts to help clear them up:
- Fevers do not always need to be treated. If your child is drinking fluids and acting relatively normal, you don’t have to reduce the fever. Let it do its job!
- A high fever does not always mean a serious illness. The number on the thermometer is less important than how your child looks and acts.
- Fevers do not cause brain damage. Only extremely high temperatures (above 108°F) can cause harm, and the body rarely reaches this level naturally.
- Febrile seizures are scary but not dangerous. Some children between 6 months and 5 years may experience a seizure due to a rapid rise in temperature, but these are usually brief and do not cause long-term harm.
When to Be Concerned About a Fever
If you are ever unsure about your child’s fever, it’s always okay to call Pediatric Partners for guidance. Trust your instincts — if something doesn’t feel right, seek medical advice.
While most fevers are not dangerous, there are times when medical attention is needed.
Seek care if:
- Your child is under 3 months old and has a temperature of 100.4°F or higher.
- Your child has a weakened immune system due to a medical condition or treatment.
- The fever is persistently high (above 104°F) and comfort cannot be managed at home.
- The fever lasts more than 5 days.
- Your child has severe symptoms, such as difficulty breathing, a stiff neck, persistent vomiting, a rash, or extreme lethargy.
- Your child has a fever seizure with the following conditions:
- it's your child's first fever seizure
- the seizure lasts more than 5 minutes
- your child has multiple seizures in 24 hours
- if there may be a treatable cause of fever, such as Strep throat or a urinary tract infection
- if you're concerned about your child.
- Your child is not drinking enough fluids and shows signs of dehydration (dry mouth, decreased urination, no tears when crying).
Fever Myths vs Facts
Many parents have false beliefs (myths) about fever. They think fever will hurt their child. They worry and lose sleep when their child has a fever. This is called fever phobia. In fact, fevers are harmless and often helpful. Let these facts help you better understand fever.
MYTH: Fever after vaccines should be treated aggressively and is a cause to worry.
FACT: Fever with vaccines is a common, mild, and self-limited event. It usually begins within 12 -24 hours and lasts 2 to 3 days. This is normal and harmless. It means the vaccine is working.
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MYTH: My child feels warm, so she has a fever.
FACT: Children can feel warm for a many reasons. Examples are playing hard, crying, getting out of a warm bed or hot weather. They are "giving off heat." Their skin temperature should return to normal in about 20 minutes. About 80% of children who act sick and feel warm do have a fever. If you want to be sure, take the temperature. These are the cutoffs for fever using different types of thermometers:
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MYTH: My child's temperture is normally low, so temperatures less than 100.4F are a fever.
FACT: Temperature norms are based on data from people and do not change if the baseline is changed. Temperatures are not as accurate as they seem, so pediatricians use symptoms rather than degree reading on the thermometer more to determine the seriousness of the fever.
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MYTH: All fevers are bad for children.
FACT: Fevers turn on the body's immune system. They help the body fight infection. Temperatures between 100° and 104° F (37.8° - 40° C) are good for sick children to fight the infection.
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MYTH. Fevers higher than 104° F (40° C) are dangerous and cause brain damage.
FACT: Fevers with infections don't cause brain damage. Only temperatures higher than 108° F (42° C) can cause brain damage. It's very rare for the body temperature to climb this high. It only happens if the air temperature is very high. An example is a child left in a closed car during hot weather.
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MYTH: Anyone can have a seizure triggered by fever.
FACT: Only 4% of children can have a seizure with fever. These are caused by the rapid change in body temperature, not the height of the fever.
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MYTH: Seizures with fever are harmful.
FACT: Seizures are scary to watch, but they usually stop within 5 minutes. They don't cause any permanent harm. They don't increase the risk for speech delays, learning problems, or seizures without fever.
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MYTH: All fevers need to be treated with fever medicine.
FACT: Fevers only need to be treated if they cause discomfort (makes your child feel bad). Most fevers don't cause discomfort until they go higher than 102° or 103° F (39° or 39.5° C).
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MYTH: Without treatment, fevers will keep going higher.
FACT: The brain knows when the body is too hot. Most fevers from infection don't go higher than 103° or 104° F (39.5°- 40° C). They rarely go to 105° or 106° F (40.6° or 41.1° C). While these are "high" fevers, they also are harmless ones helpful to fight the infection.
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MYTH: With treatment, fevers should come down to normal.
FACT: With treatment, most fevers come down 2° or 3° F (1° or 1.5° C). (That's a good thing - maintaining some temperature elevation helps to fight the infection!)
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MYTH: If you can't "break the fever", the cause is serious.
FACT: Fevers that don't come down to normal can be caused by viruses or bacteria. The response to fever medicines tells us nothing about the cause of the infection.
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MYTH: Once the fever comes down with medicines, it should stay down.
FACT: It's typical for fevers with most viral infections to last for 2 or 3 days and up to 5 days is considered normal. When the fever medicine wears off, the fever will come back. It may need to be treated again. The fever will go away and not return once the body overpowers the virus.
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MYTH: If the fever is high, the cause is serious.
FACT: If the fever is high, the cause may or may not be serious. If your child looks very sick, the cause is more likely to be serious.
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MYTH: The exact number of the temperature is very important.
FACT: How your child looks and acts is what's important. The exact temperature number is not.
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MYTH: Oral temperatures between 98.7° and 100° F (37.1° to 37.8° C) are low-grade fevers.
FACT: These temperatures are normal. The body's normal temperature changes throughout the day. It peaks in the late afternoon and evening. A true low-grade fever is 100° F to 102° F (37.8° - 39° C).
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MYTH: We are only contagious during the time of a fever.
FACT: We are most contagious during the time of fever and for 24 hours after the fever breaks, but even if the temperature is brought down during the period of fever and after the fever breaks, we can continue to be contagious.
Here’s a breakdown of the contagious periods for common viral infections, including influenza, COVID-19, hand-foot-and-mouth disease, norovirus, and the common cold:
1. Influenza (Flu)
- Contagious period: 1 day before symptoms begin to 5-7 days after becoming sick.
- Young children and immunocompromised individuals may be contagious for longer—up to 10+ days.
- When to return to activities: Once fever-free for at least 24 hours without fever-reducing medication and symptoms are improving. Wearing a mask through at least day 10 can help prevent spread to others since you may still be contagiousl
2. COVID-19
- Contagious period:
- 2 days before symptoms start to at least 5 days after symptoms begin.
- Some people remain contagious for 10+ days, especially if symptoms are severe or they are immunocompromised.
- Guidance for returning to activities:
- Isolate for at least 5 full days after symptom onset (or positive test if asymptomatic).
- After day 5, if symptoms are improving and fever has been gone for 24 hours, wear a high-quality mask through at least day 10 around others.
3. Hand-Foot-and-Mouth Disease (HFMD)
- Contagious period:
- Most contagious during the first few days of illness, especially when fever and mouth sores are present.
- The virus can shed in stool for weeks after symptoms resolve, meaning it can still be spread through contact with contaminated surfaces.
- When to return to activities:
- Once fever is gone for 24 hours and child is feeling well enough for normal activities.
- If there are open blisters, some schools/daycares may require them to be fully healed but this is not the standard recommendation since it does not define the contagious period.
- Good handwashing and proper cleaning of surfaces (especially toys and frequently mouthed objects) is essential.
4. Norovirus ("Stomach Flu")
- Contagious period:
- From the moment symptoms begin (vomiting, diarrhea) until at least 2-3 days after symptoms stop.
- Some people shed the virus in their stool for up to 2 weeks, especially young children.
- When to return to activities:
- Wait at least 48 hours after last episode of vomiting or diarrhea before returning to school, work, or other activities.
- Good handwashing and proper cleaning of surfaces (especially toys and frequently mouthed objects) is essential. Hand sanitizers do NOT work against this virus.
5. Common Cold (Rhinovirus & Other Cold Viruses)
- Contagious period:
- 1-2 days before symptoms start and continues for up to 10 days after symptoms appear.
- Children and immunocompromised individuals may shed the virus longer.
- When to return to activities:
- Since colds can last 1-2 weeks, children and adults can return to school or work when symptoms are mild, fever is gone for 24 hours, and they feel well enough to participate.
- Encourage handwashing and wearing a mask for a couple weeks after infections to minimize spread.
